Could you specify which serial port you are using to communicate with other microcontroller?
For example, if you are using the communication Port(serial2), you can set the baudrate when opening the port in the Arduino sketch code.
Serial2.begin(1000000); //Initialize the Serial Port 2 baudrate to 1Mbps
If you elaborate more on your development environment, I think I can give you more related information.
When each motion is called in the task, there are gaps between motions.
This is because the code checks whether or not the previous motion is completed, and then it takes time to load the saved motion from given index number.
If you want to create a seamless motion, you need to create a motion that contains all motions as you did in the second image.